Five continuous cultures of cells derived from both adult and embryonic Anolis cardinensis fail to exhibit sensescene in vitro. The continuous cultures have been carried for from 118 CPD to over 2,000 CPD. In all cases diploid cells remain and two normally differentiating cultures have been studied in detail, i.e., smooth muscle derived from the lung and striated skeletal muscle derived from both adult and embryonic Anolis. During the next project period we plan to use our library of frozen cell stocks to critically follow: 1) ploidy; 2) percent cycling cells; 3) heterogeneity of cell type; and 4) test for any indications of subtle transformation in our continuous cultures. This study proposes to test the generalizability of the Hayflick Model of in vitro senescence.